1. Field of the Invention
The invention relates to a milling cutter having the features of the preamble of claim 1, and of the preamble of claim 9.
2. Description of Related Art
Such milling cutters, in particular round-head milling cutters, are known, for example, from WO 2008/116446 A1 and DE 697 29 945 T2.
In the present case, round-head milling cutters, also known as ball milling cutters, are understood generally to mean those shank milling cutters that have a tool head comprising a number of cutting teeth that each comprise a cutting edge. The respective cutting edge in these cases first runs radially outward, approximately in the radial direction, in a front-side radial portion of the respective cutting tooth, and passes, via an arcuate course, into a circumferential axial portion of the cutting tooth extending substantially in the axial direction. A ball milling cutter in the narrower sense is understood in this case to mean a ball head geometry in which the respective cutting edge runs, immediately from the center of the drill bit, along an arcuate line and has a constant radius. Ball milling cutters in the present case are also understood to mean milling cutters having a toroidal geometry, in which the cutting edge regions have differing radii, or can also run rectilinearly in the radial portion and/or axial portion.
Such round-head milling cutters are used to produce “ball races” in only one process step. Such ball race milling is used, in particular, in the field of automobiles, particularly in the field of wheel suspensions, to enable an articulated wheel fastening to be achieved. The desired ball race in such cases is made on the circumferential side of a metal disk, traversing the latter.
Owing to the high numbers of pieces, the process in such cases is a mass production process. Accordingly, what is important is a process speed that is as high as possible with, at the same time, a good quality of machining without any reworking steps. Furthermore, it is necessary for the tool to have a long service life, in order that the production process is not encumbered by a multiplicity of necessary tool changing operations. In any case, fundamentally, there is the problem that the machining quality becomes critical as the process speed increases, or that the cutting edges do not withstand being subjected to greater load. In particular, there is also the problem of an uneven machining process that subjects the tool to stress, as well as the problem of burr formation.
According to WO 2008/116446 A1, a milling head made of solid hard metal is provided, in which cutting inserts are used supplementally to realize the cutting edges. The milling head is connected to a tool holder via an intermediate piece. In the case of the design according to DE 697 29 945 T2, the milling head is composed of a material produced by powder metallurgy, and is connected to a tool holder via a tie rod, made of steel, that defines a clamping shank. In both known embodiment variants, coolant channels are routed into the tool head, which coolant channels open out into chip flutes realized between the individual cutting teeth.